example sync functions that demonstrate best practices for common models

There are some standard use cases that would likely have very similar sync functions. Three or four that example sync functions illustrating how those would look in those use cases, such as:
- POS for a company with several different restaurants
- product catalog with unidirectional relationship between central server -> mobile client
- bird field research that shares all gathered data with all subscribed users
-- could be more nuanced
- the infinite campus real-time feedback vs undirectional content distribution case